. Hepatitis B virus (HBV) is a hepatotropic virus that is a major public health concern worldwide. While a recombinant surface antigen vaccine is available, there is no effective treatment for the millions of individuals who are chronically infected. The objective of this proposal is to develop peptide therapeutics that will generate cytotoxic T lymphocytes (CTL) in vivo and may ameliorate chronic HBV infections. These molecules may also be useful as prophylactic vaccines. This study aims to 1. define the 9-10 amino acids that constitute the core CTL epitopes; 2. modify these peptides to enhance their stability, facilitate uptake into antigen presenting cells and to enhance immunogenicity by adding helper epitopes; 3. to determine if these peptides can generate CTL's in vivo (in HLA-A2 transgenic mice).